I would not give her any fruit. Ferret (weasels) are carnivores. I would stay on the safe side and say no to fruit.
I will also say no to the dog shampoo. Most things made for dogs are too harsh for ferrets. Go for things made for kittens (do not bathe her too often, it will cause dry skin and actually make her smell worse). Dry kitten food is alright to give her if you cannot find ferret food (do not give her the ferret food from walmart=bad stuff).
If you want her weight back up you can give her pedialyte or a favorite ferret treat called duck soup. You can also give her 2nd generation turkey or chicken baby food.
I would stay away from the peanut butter aswell, peanut better has been known to cause choking. Though you can get Bandit's peanut butter ferret treats at your lps. :)
As for litter you can use dry stove wood pellets or non clumping, dust free cat litter. :)
Bettas - Giovanni (HM), Burly (HMPK Giant)
Cats - Drew, Tao, Jakke